A replication session can be implemented using various replication modes, such as synchronous (sync) replication, asynchronous (async) replication, and active/active replication, which as also known as metro replication.
Sync replication is a business continuity process that mirrors data updates between two systems to prevent data loss and downtime. When sync replication is turned on for a production storage object, the system mirrors the data to a target system as part of handling write requests from an initiator, and only responds to the initiator after the writes have been persisted on both the source and target systems.
In asynchronous (async) replication, once data has been written to a primary storage or production location, additional write operations to the primary storage can be performed without having to wait for the secondary or target storage site to complete its write operations.
Active/Active replication (also known as “metro replication”) enables multiple database instances to support a common application. Synchronization among the databases is achieved through bidirectional replication capabilities.